1. Filed of Invention
The present invention relates to an air/water-tight slide fastener used for a flexible container for transportation of liquid, protective clothes, diving suits, and the like, and particularly to an air/water-tight slide fastener wherein end stops are firmly attached thereto and reliable air/water-tightness can be enjoyed.
2. Description of the Related Art
Strict air/water tightness is required for a flexible container for transpiration of liquid, protective clothes, diving suits, undersea tunnel and the like articles which are subjected to high pressure. Air/water-tight slide fasteners comprised of an air/water-tight slide fastener chain, a slider and end stops are much used for these fields. One example of air/water-tight slide fasteners of this type is disclosed in Japanese Utility Model Publication No. 4-36657 filed by the applicant of this patent application.
A fastener element of this conventional slide fastener is comprised of an arrow-shaped coupling element having a coupling head formed on its one end and a substantially U-shaped clamping element. One longitudinal edge of the air/water-tight fastener tape is folded thereon in Ω shape and wrapped around a flange of the coupling element. The longitudinal edge wrapped around the flange of the coupling element is then firmly clamped by the clamping element from both front and rear side of the air/water-tight fastener tape. A plurality of fastener elements are attached to the longitudinal edge of the air/water-tight fastener tape at a predetermined interval, so that an air/water-tight fastener stringer is produced.
A backing patch is integrally attached to one end of the air/water-tight fastener tapes. A slider is introduced into a pair of fastener stringers having a predetermined length. An upper and lower end stops are integrally formed by injection molding process to an upper and lower ends, respectively, of the fastener stringers, to thus provide the air/water-tight slide fastener. Each of these upper and lower end stops is comprised of substantially parallelepiped blocks. The block has a narrow flange portion or fin integrally formed therearound. The flange portion is welded to both the fastener tape and the backing patch across the boundary therebetween.
The air/water-tight slide fastener thus produced is attached all around the periphery of, for example, a flexible container except a little part of the periphery in order to open and close the container. The opening edges of the opening formed in the flexible container are attached to the air/water-tight tapes and the backing patch through high-frequency welding or supersonic welding, spaced a predetermined distance outwardly from the position where the flange portions of the upper and lower end stops and the slider are located.
This type of water/air-tight slide fastener is intended to be attached to an article such as a collapsible flexible container used for containing certain liquid in transporting it with a track or a freight car exclusively used for that purpose. After the track or the freight car reaches the destination, the liquid is shifted from the collapsible containers to other containers. The collapsible container is collapsed when out of use. Most of liquid that is transported with the collapsible containers is drinking water or various beverage and the collapsible containers must be kept clean at all times. Whenever transportation may finish, the collapsible containers must undergo the steps of cleansing, sterilization and drying. In these steps, the air/water tight tape of the slide fastener attached to the container is also liable to be folded around the end stops.
FIG. 9 shows how the conventional air/water-tight slide fastener is folded. FIG. 9 is a perspective view of an essential part of the slide fastener as viewed from the side opposite to the side where the slide fastener is folded. A common end stop 114 of the fastener stinger 117 is comprised of a block 114a and a narrow fin or flange portion 114b integrally formed around the block 114b and extending outwardly therefrom. As shown in FIG. 9, when the slide fastener is folded around the end stop 114, the air/water-tight tape 111 is abruptly folded longitudinally thereof on the boundary between the block 114a and the flange portion 114b of the end stop 114. At this moment, part of the air/water-tight tape 111 is liable to be peeled off the flange portion 114b, so that the air-tightness is lost, which is fatal to this type of air/water-tight slide fastener
Specifically, when the flexible container 30 is folded, unexpected severe stress is exerted upon the flexible container 30, tending to turn or bend the air/water-tight fastener tapes 111 attached to the flexible container 30 along the boundary between the block 114a and the flange portion 114b of the end stop 114, whereon the flange portion 114b is forced to restore into the original unfolded disposition due to its resiliency and at the same time that part 111a of the air/water-tight tapes 111 which lies along the lower edge of the flange portion 114b is subjected to direct and strong bending stresses against the resiliency of the flange portion 114b. Consequently, the air/water-tight tape part 111a gets peeled off from the flange portion 114b. This peel-off phenomenon of the air/water-tight tape 111 would destroy or derogate from the air/water-tightness which is an essential function of the air/water-tight slide fastener 110.
The conventional air/water-tight slide fastener disclosed in the above-mentioned utility model publication is often attached to the opening of the flexible container so as to open and close the container. This air/water-tight slide fastener is repeatedly subjected to severe stresses when the container is folded and unfolded during laundering, sterilization and drying thereof. Even if the peeled-off portion is small, as bending stresses are repeatedly exerted upon that part of the air/water-tight tape that lies along the lower edge of the flange portion of the end stop, the peeled-off portion grows bigger and bigger, and eventually the slide fastener loses air/water-tightness and water leakage occurs therethrough. This is a problem with the conventional air/water-tight slide fastener.
Furthermore, portable sports gears such as diving suits to which such air/water-tight slide fastener is attached are collapsed and sometimes placed on a floor when out of use, and these sports gears are sometimes trampled down. That part of the air/water-tight tapes which lies along the lower edge of the flange portion of the end stop is subject to direct and strong bending stresses, which leads to deterioration of air/water-tightness.
This invention is intended to overcome the above problem. Specifically, a purpose of the present invention is to provide this type of air/water-tight slide fastener which keeps air/water-tight and durable for a long period of time, and which would not suffer from the peeled-off phenomenon, even if it were forcibly folded longitudinally thereof.